A wide variety of automatic and semi-automatic chemistry analyzers are known and are commercially available. These analyzers mimic and automate a variety of test procedures and methodologies which were previously performed manually. A typical chemistry analysis, whether performed automatically, semi-automatically or manually, involves a variety of samples to be tested and analyzed, as well as a varity of diluents and reagents to be used.
A typical biochemical analysis involves the addition of a sample to a reaction vessel, following which a reagent is added thereto. The mixture is stirred and a second or additional reagents may be thereafter added, all followed by stirring. After sufficient time for a desired reaction to take place has occurred, the liquids in the reaction vessels are analyzed by fluorescent, radioactive or colorimetric techniques.
In conducting an immunological analysis, such as an enzyme-immono-assay ("EIA") analysis, a measured amount of a sample, which may contain a measured amount of a diluent, is added to a reaction vessel. The vessels also hold a carrier, such as a glass or synthetic resin bead, which has an antibody or antigen fixed on the surface thereof. A first or conjugate reagent is then added the ultimate effect of which is to bind the selected antibody or antigen to the bead. After removing the first reagent and washing or rinsing, following passage of a selected time, next added to the reaction vessel are second and third reagents. Following the passage of another selected time, during which a desired reaction takes place, which separates the bound and the free antibodies or antigens and to otherwise react with substances bound to the bead to produce a test liquid, which is ultimately withdrawn or decanted from the test vessel and colorimetrically analyzed by a photometer. The foregoing description applies generally to all EIA tests, including heterogeneous EIA tests of both the competitive and the sandwich types.
If semi-automatic or automatic apparatus is provided to conduct the above testing steps, then washing and rinsing of reaction vessels, in addition to that required directly for purposes of the test, is clearly required for a subsequent test to be conducted on different samples.
Typical automatic chemistry analyzers include a plurality of reaction vessels, a plurality of containers for samples, and a plurality of containers holding various reagents and water. In a typical prior art chemistry analyzer, the various liquid samples and reagents are removed from the sample containers and the reagent containers and are placed into and removed from the reaction vessels by a facility which comprises a robotic arm or head.
The robotic arm is mounted for rotational movement about a vertical axis and is also capable of rotating about a horizontal axis so that the head may be moved vertically up and down. The arm typically carries one or more hollow tubes, or hypodermic needle-like members, and flexible tubing connecting the tubes or members to appropriate pumps. The robotic arm and the pumps are used to remove a sample from a sample container, to place the removed sample into a reaction vessel, to remove a selected first reagent from a reagent container, and to then place the reagent into the reaction vessel holding the sample. In order to avoid contamination, for example of the reagent by the sample, the tubes may be first immersed in a "home" position well, which contains rinsing water, after the sample has been placed in the reaction vessel but before removal of the reagent. The rinsing water is removed from the passes through and rinses the needless and the tubing and is transported to a waste liquid container at a remote location.
After the appropriate reaction has taken place in the reaction vessel, the robotic arm is operated so as to remove the first reagent from the reaction vessel, rinse the vessel and the head, place the second and third reagents in the vessel--rinsing the second reagent from the needle before placing the third reagent--and transporting the contents of the vessel for testing by a photometer or the like, to which the liquid is conducted by the tubing and the pumps. If an EIA test is being performed, the above general description of the prior art apparatus is a bit more lengthy and complicated because the glass bead in the reaction vessel is rinsed and washed several times before fluid is decanted from the reaction vessel for transmission to the photometer.
In most prior art automatic chemistry analyzers, the various vessels and containers are carried in a moveable carrier, typically a circular carrier. Movement of the robotic arm, and the various movable carriers, is appropriately coordinated under the control of a programmed microprocessor to automatically effect a plurality of tests on various samples. In one preferred arrangement, the reaction vessels comprise compartments formed in a quarter-circular member called a sector. Four sectors are carried by a circular turntable, which is selectively operated by a stepping motor under the control of the microprocessor. The sectors are positioned at the periphery of the turntable. Also carried by the turntable, and closer to the center thereof, are sample containers. When the turntable is at a selected position, the robotic arm may be operated so that its needle may be inserted into a selected reaction vessel and/or a selected sample container for placement or removal of liquid thereinto. Thus, the needle of the robotic arm can reach all of the reaction vessels and all of the sample containers, but can do so only in conjunction with rotation of the turntable or carrier to appropriately position each thereof. The reagent containers are contained on the circumference of a circle, the center of which defines the vertical rotation axis of the robotic arm. Thus, the carrier for the reagent containers may be stationary since the needle-like member of the robotic arm can access each of the reagent containers.
Some difficulty has been experienced in making a chemical analyzer of the type described above compact and in adapting such an analyzer in convenient fashion to perform both general and EIA tests. Specifically, as previously noted, EIA tests involve the use of solid-phase bead technology. When these tests are automated, they involve the insertion of the robotic arm's needle-like member into the reaction vessels both to deposit and to remove liquids therein. Because of the extent of the insertion of the needle-like member necessary to ensure that liquid in the vessel is removed, it has been found that the presence of the bead in the container can interfere with and/or block the operation of the needle-like member in placing or withdrawing liquids. One solution to this problem would be to make the reaction vessel sufficiently large or deep so that the presence of the bead would cause no interference with the needle-like member of the robotic arm. However, following this course is counter to the trend of making automatic chemical analyzers as compact and low profile as possible. One solution to the foregoing problem is described in U.S. Pat. No. 4,837,159, which involves the use of specially shaped reaction vessels which add to the cost and complexity of the equipment.
Prior art manual techniques, particularly as they relate to EIA tests, involve not only multiple rinsing steps but also involve the need to stir, shake, mix or agitate a mixture of liquids at various times. The prior art provides for a variety of means for stirring or agitating liquids involved in chemical analyses, but these tend to involve rather complicated mechanical structures in addition to the other structures required for automatic analysis. For various stirring or agitating apparatus, see the following U.S. Pat. Nos. 4,774,055; 4,383,041; 4,981,801; 4,200,607; 5,104,807. There is a need for a simple, yet effective, method of stirring, mixing or agitating fluids in the reaction vessels which does not add significantly to the size, cost and complexity of the automatic apparatus.
The prior art also recognizes the need to control the temperatures of the various liquids involved in chemistry analyzing. In the automatic or semi-automatic apparatus of the prior art, temperature control is effected typically by maintaining the environment in the vicinity of one or more of the liquid containers involved at a given temperature so that reactions using such liquids are carried out at or near such known temperature. See, for example, U.S. Pat. No. 4,981,801 and 4,200,607. It is felt to be desirable to provide improved apparatus for more accurately maintaining the temperature of the various liquids involved in chemical analysis by automatic and semi-automatic equipment.
A primary object of the present invention is the provision of an improved chemistry analyzer of the type described above, which eliminates some of the disadvantages of prior art apparatus, and achieves the aforenoted goals related to needle interference by the beads involved in EIA analyses, agitation or stirring of liquid mixtures in conducting chemical analyses, and temperature control.